Home was built in 1965. Conventional tank and leach field. 30 years ago, I had a home inspector before we closed the purchase. He filled the tub and then let it drain. Based on the backup/slow drain, he recommended a new leach field. A new field was installed. Since then, I've pumped the tank every 3 -5 years. The hard rule here is only toilet paper and what was eaten goes in the toilet. Cooking grease is collected for the trash. Haven't any issue with bleach or such in 30 years.
PS: I did install risers on inlet and outlet to avoid digging and landscape disturbance.